Fuel injector of air-cooled compression ignition engine



May 26, 1959 4 o s 2,887,994

FUEL INJECTOR OF AIR-CObLED COMPRESSION IGNITION ENGINE Filed July 24,1957 2 Sheets-Sheet II Am 33 I 14 20 i 5 11) all 18 i 2154, 310 5 12 fluj I Inven or Hiker-to Jar 'ye Mar/is A. J. MORRIS May 26, 1959 FUELINJECTOR 0F AIR-COOLEID COMPRESSION IGNITION ENGINE Filed July 24', 19572 Sheets-Sheet 2 In 1101 or fllber/o z/mye M rris a United States PatentFUEL INJECTOR OF AIR-COOLED COMPRESSION IGNITION ENGINE Alberto JorgeMorris, Dursley, England, assignor to R. A. Lister & Company Limited,Gloucestershire, England, a British company Application July 24, 1957,Serial No. 673,898 Claims priority, application Great Britain May 23,1957 Claims. (Cl. 123-32) This invention relates to compression ignitionengines and fuel injectors therefor.

According to the present invention, a fuel injector for acompression-ignition engine has an injector body and a nozzle element,the injector body comprising a main body part housing moving parts ofthe injector and a nut part threaded on the main body part to hold thenozzle element in abutment with one end of the main body part, saidinjector affording two external peripheral locating surfaces for thelocation of the injector in an engine, which locating surfaces arespaced apart lengthwise of the injector, one of said locating surfacesbeing provided on the injector nut adjacent the end thereof nearest thenozzle, and the other locating surface being provided on the main bodypart, at least part of the external surface of the injector between thetwo locating surfaces being provided with cooling fins. According to onepreferred arrangement of the present mvention, the nut part has anannular portion projecting [from the locating surface thereon, theinternal surface of which portion closely surrounds the tip of thenozzle element and the external surface of which portion isfrusto-conical so that the portion tapers in radial thickness in adirection away from the locating surface towards the tip of the nozzleelement.

It is found that by providing such a projecting portion on the nutmember, cooling of the injector is markedly improved, and theimprovement in cooling is such that finning is needed only on the nutpart.

Preferably, also the internal and external surfaces of the projectingportion of the nut part of the injector meet in an edge at their endsremote from the locating surface. The nut part may if desired be formedin two pieces, one piece being threaded on the main body part to holdthe nozzle element in abutment with one end of the main body part, andthe other piece affording the locating surface and said projectingannular portion, the two pieces of the nut being in abutment with eachother lengthwise of the injector.

According to the invention, moreover, a compression ignition enginecomprises one or more injectors as above set forth, and the engine hasspaced walls which afiford surfaces co-operating with said peripherallocating surfaces to locate the injector or injectors, and havingprovision for causing a flow of cooling air between said walls, wherebycooling air flows over the cooling fins of the injector or injectors.

According to a feature of the invention, where the injectors have atapering projecting portion, the wall adjacent the engine combustionspace which co-operates with the locating surface on the nut part, has ahole there in through which the nozzle element projects and the holetapers to receive the annular projecting portion of the nut part with asmall clearance.

According to a preferred feature of the present invention, the walls areafforded for each engine cylinder respectively by a finned cylinder headand by a heavy clamping plate carrying the valve rockers, resting on thefins of the cylinder head and secured to the engine to restrain bendingof the cylinder head, the air inlet duct and the exhaust duct project toone side of the head, and the fins on the head are shaped to maintainseparate cooling air flows over the head in the region of the inlet ductand inlet port on the one hand and in the region of the exhaust duct andexhaust port on the other hand and to deflect the relatively cool airflowing in the region of the inlet port to flow around the fuel injectorwhere it extends between the walls.

In one arrangement according to this feature of the invention, thecylinder head and clamping plate are located relatively by making theexhaust valve guide a press fit in each of these parts, and by makingthe inlet valve guide a press fit in the cylinder head and engaging theinlet valve guide in the clamping plate through a sealing ring.

Two constructions of fuel injector and air-cooled compression-ignitionengine of this invention will now be described with reference to theaccompanying drawings in which:

Figure 1 is a section through the engine on the axis of a cylinder,

Figure 2 is a plan view of the cylinder head,

Figure 3 is a view corresponding to Figure 1 of a second form ofinjector, and

Figure 4 is an end view of the injector shown in Figure 3.

Referring to the drawings, the engine comprises an externally finnedcylinder 10 in which works a piston 11 of any convenient kind, acylinder head 12, and clamping plate 13.

The cylinder head 12 has formed in one piece with it an air inlet duct14 leading from the air manifold (not shown) to an air inlet port in thehead, an exhaust duct 15 leading from an exhaust port to an exhaustmanifold (not shown), a pair of bored upstanding pillars 16, 17 forreceiving the inlet and exhaust valve guides 18, 19 respectively. Theinlet valve guide 18 has an interference fit in the head 12 but has aclearance from the hole in the clamping plate 13 into 'which it projectsand a circular-section ring 20 is provided around the guide 18 toprevent passage of lubricating oil through the hole to below theclamping plate 13. The exhaust valve guide 19 is a press fit in both thehead l2-and clamping plate 13.

The cylinder head 12 is also provided with a hole through which a fuelinjector 21 extends. The hole is shaped to afford a seat 22 for one endof the injector and has a frusto-conical portion 23 beyond the seatextending to the cylinder space.

The cylinder head is also provided with finning which is designed toprovide eflicient cooling of the injector 21. The finning comprises acentral fin 24 which separates the air flows over the duct 14 from thatover duct 15 and is curved at its downstream end to deflect air flowingbetween it and the duct 15 towards the airstream flowing over fins 25 onthe duct 15 and pillar 17, thus to prevent this air stream which isrelatively hot from contacting the injector 21. The duct 14 and adjacentparts of the head 12 are provided with fins 26 and a continuous wall 27which are shaped to deflect the relatively cool air stream flowing overthe duct 14 and pillar 16 to flow over the injector 21 to cool it. Theprovision of a separate clamping plate 13 and the design of the finningenables the cylinder head to be produced by a simple casting methodavoiding the use of complicated coring as would be required if the topwall of the cooling air space is made in one with the head 12. Thefinning is also designed to permit a high velocity air flow ofsubstantially constant speed through the air spaces between the head 12and clamping plate 13.

The clamping plate 13 rests oh the finning and is designed to preventbending of the head. The clamping plate has mounted on it a pair ofpedestals 28 carrying the valve rockers 29 and is formed with wells 33receiving the valve springs 31. Between the pedestals 28, the clampingplate is provided with a cylindrical-walled hole 32 through which theinjector 21 projects, and the injector is retained in position by acrOSs bar 33 bearing on the upper end of the injector 12 and secured tothe rocker pedestals 28.

In order to ensure eflicient cooling of the injector 21, an improvedinjector is employed. This comprises a main injector body part 21acontaining any moving parts of the injector and formed with a pair offlanges 21b. The flanges 21b occupy the hole and receive between them asealing ring 210; the flanges 21b, ring 21c and the hole 32 afford afirst location for the injector. The injector further comprises a nozzleelement 21d which is held in abutment with the end of the main body part21a by a nut part Zle threaded on the main body part.

The nut part 21c is provided with finning 34 over the portion thereofwhich lies in the air space, with a flange 35 which bears on the 'seat22 and provides a second location for the injector, and with an annularportion 36 which projects from the flange 35, surrounds the tip of thenozzle element 21d with a small clearance, say .005 inch, and has anexternal surface of frusto-conical form so as to have a clearance, ofsay .015 inch, from the frusto-conical bore portion 23 and so that theportion 36 tapers in thickness away from flange 35 towards the cylinderspace. The conical surface of the portion 36 and its bore meet adjacentthe end of the nozzle element substantially in an edge. It is found thatthe provision of the frusto-conical portion 36 and the finning 34markedly improves the cooling of the injector. I

If desired, the nut part 21a just described may incorporate parts madefrom material having a high heat conductivity. In one such arrangementthe nut 212 comprises a cylindrical threaded part made of a metal havinghigh tensile strength, which part serves to secure the nozzle element21d in abutment with the main body part 21a, and an outer sleeve partwhich abuts and is a close sliding fit over the cylindrical part andwhich affords the cooling finning 34, the flange 35 and annular portion36. The outer sleeve part is made from a metal having high heatconductivity so that heat is conducted more rapidly away from the tip ofthe nozzle element.

In an alternative arrangement, the part affording the flange 35 andannular portion 36 is made separately from the threaded nut part 21:2,the two parts abutting one another axially of the injector. In this casethe part affording the flange 35 and portion 36 is made a close slidingfit over the tip of the nozzle element 2M, and is made from a highlyconductive metal with the result that the rate of conduction of heataway from the nozzle tip is increased considerably. The threaded nutpart is of course made from material, such as steel, having a hightensile strength. Pinning 34 is provided on the threaded nut part, andin addition the part affording flange 35 may have a suflicient axiallength to be provided with one or more radial cooling fins at its endabutting the nut part.

The engine is also provided with a rocker cover 37 and the normaldecompression lever 38.

The cooling air supply may be effected in any convenient manner; forinstance a cowling may be provided at the left hand side of the engine(as viewed in Figure 1) to convey the cooling air to this side of thecylinder and the adjacent end of the cooling air space between the head12 and clamping plate, the air flowing from the engine at the right handside.

Referring now to Figures 3 and 4, the body member of the injectorcomprises a substantially tubular main body part 40, in which aremounted the moving parts of the injector, and a nut part 41 which isthreaded on the main body part 40 and secures an injector nozzle mem- 4%her 42 thereto. For this purpose the nut 41 is provided with an internalannular shoulder 43 which co-operates with a corresponding externalannular flange 44 on the injector nozzle member 42, the flange 44 beingso located that the lower portion of the injector nozzle member 42protrudes below the lower end of the nut 41. The external surface of thenut 41 is accurately machined at its lower end to afford a spigotlocation 41a in the cylinder head for the lower end of the injector, thelower edge of the spigot location 41a being slightly chamfered.

The cylinder head of the engine comprises an inner wall 45 and an outerwall 46 with an air space between the walls, the lower side of the innerwall 45 being adjacent the working cylinders. A supply of cooling air iscirculated between the two walls.

The inner wall 45 has a drilling 47 at the location of each injectoropening into a cylinder of the engine, and the drilling has an enlargeddiameter portion 48 at its end remote from the cylinder affording alocating diameter and an annular abutment 49 at the change of diameter.The outer Wall 46 of the cylinder head has a corresponding aligned hole50 bored to allow the insertion of the injector. When the injector isinserted the nozzle and body portions pass through the hole 50 in theouter wall 46 of the cylinder head and the nozzle member 42 fits intothe hole 47 in the inner wall so that the end of the nozzle member 42 islevel with the adjacent portions of the bounding surface of thecylinder. The spigot portion 41a machined on the nut 41 engages in thecorresponding enlarged diameter portion 48 of the drilling 47 and a gassealing ring 51 is interposed between the end of the nut 41 and theannular abutment 49. The injector is held down securely on to theabutment.

The injector body is provided with a locating flange 52 to engage theouter wall 46 of the cylinder at the location of the hole 50. A groove53 is machined on the periphery of the flange 52 and contains a rubberring 54 to prevent leakage of lubricating oil into the space between theinner and outer walls of the cylinder head. Alternative types ofoil-sealing gland may be used.

In this embodiment, peripheral cooling fins 55 are provided on theexternal surfaces of the main body part 40 and nut 51 of the injectorbody between the spigot location 51a and the locating flange 52. Theflow of cooling air between the inner and outer walls 45, 46 of theengine cylinder head thus passes over the finned portions of theinjector body to ensure effective cooling of the injector.

The nut is normally made on an automatic lathe and thus the additionalcost of machining the cooling fins on it is very small. In additionWhere the nut is made from hexagonal bar, the necessary flats for thespanner are already provided and the cooling fins 55 are formed bycutting into the flats.

I claim:

1. A fuel injector for a compression ignition engine having an injectorbody and a nozzle element, the injector body comprising a main body parthousing moving parts of the injector and a nut part threaded on the mainbody part to hold the nozzle element in abutment with one end of themain body part, said injector affording two external peripheral locatingsurfaces for the location of the injector in an engine, which locatingsurfaces are spaced apart lengthwise of the injector, one of saidlocating surfaces being provided on the injector nut adjacent the endthereof nearest the nozzle, and the other locating surface beingprovided on the main body part, at least the external surface of the nutpart between the two locating surfaces being provided with cooling fins.

2. A fuel injector according to claim 1, wherein the nut part has anannular portion projecting from the locating surface thereon, theinternal surface of which portion closely surrounds the tip of thenozzle element and the external surface of which portion isfrusto-conical so that the portion tapers in radial thickness in adirection away from the locating surface towards the tip of the nozzleelement.

3. An injector according to claim 2, wherein the internal and externalsurfaces of the projecting portion of the nut part of the injector meetin an edge at their ends remote from the locating surfaces.

4. An injector according to claim 2 wherein said nut part is formed intwo pieces, one piece being threaded on the main body part to hold thenozzle element in abutment with one end of the main body part, and theother piece aflording the locating surface and said projecting annularportion, the two pieces of the not being in abutment with each otherlengthwise of the injector.

5. An injector according to claim 4, wherein said internal surface is aclose sliding fit around the tip of the nozzle.

6. An injector according to claim 4, wherein the threaded piece of thenut is cylindrical, and said other piece of the nut affords a sleeveclosely surrounding the threaded portion and is formed internally withthe cooling fins.

7. An injector according to claim 4, wherein said other piece of the nutis formed from a material having a high heat conductivity.

8. A fuel injector according to claim 1, wherein the nut part ishexagonal and the cooling fins are formed by cutting into the flats.

9. A fuel injector according to claim 8, wherein the main body part isalso provided with cooling fins.

10. A compression-ignition engine having at least one fuel injector asclaimed in claim 1, wherein the engine has spaced walls which affordsurfaces co-operating with said peripheral locating surfaces to locatethe injector, and having provision for causing a flow of cooling airbetween said walls, whereby cooling air flows over the cooling fins ofthe injector.

11. An air-cooled compression-ignition engine as claimed in claim 10,wherein the wall adjacent the engine combustion space which co-operateswith the locating surface on the nut part, has a hole therein throughwhich the nozzle element projects and the hole tapers to receive theannular projecting portion of the nut part with a small clearance.

12. An air-cooled compression-ignition engine as claimed in claim 11,wherein the walls are alforded for each engine cylinder respectively bya finned cylinder head and by a heavy clamping plate carrying the valverockers, resting on the fins of the cylinder head and secured to theengine to restrain bending of the cylinder head, the air inlet duct andthe exhaust duct project to one side of the head, and the fins on thehead are shaped to maintain separate cooling air flows over the head inthe region of the inlet duct and inlet port on the one hand and in theregion of the exhaust duct and exhaust port on the other hand and todeflect the relatively cool *air flowing in the region of the inlet portto flow around the fuel injector where it extends between the walls.

1'5. An air-cooled compression-ignition engine as claimed in claim 12,wherein the cylinder head and 6 clamping plate are located relatively bymaking the exhaust valve guide a press fit in each of these parts, andby making the inlet valve guide a press fit in the cylinder head andengaging the inlet valve guide in the clamping plate through a sealingring.

14. A fuel injector for a compression ignition engine having an injectorbody and a nozzle element, the injector body comprising a main body parthousing moving parts of the injector and a nut part threaded on the mainbody part to hold the nozzle element in abutment with one end of themain body part, said injector affording two external peripheral locatingsurfaces for the location of the injector in an engine, which locatingsurfaces are spaced apart lengthwise of the injector, one of saidlocating surfaces being provided on the injector nut adjacent the endthereof nearest the nozzle, and the other locating surface beingprovided on the main body part, at least the external surface of the nutpart between the two locating surfaces being provided with cooling fins,said nut part also having an annular portion projecting from thelocating surface thereon towards the tip of the nozzle element, whichannular portion closely surrounds the tip of the nozzle element andtapers in radial thickness in a direction from the locating surfacetowards the tip and terminates adjacent the tip in a sharp edge.

15. A compression ignition engine having a combustion space and at leastone fuel injector for delivering fuel to said combustion space, saidfuel injector comprising an injector body and a nozzle element, theinjector body comprising a main body part housing moving parts of theinjector and a nut part threaded on the main body part to hold thenozzle element in abutment with one end of the main body part, saidinjector affording two external peripheral locating surfaces for thelocation of the injector in an engine, which locating surfaces arespaced apart lengthwise of the injector, one of said locating surfacesbeing provided on the injector nut adjacent the end thereof nearest thenozzle, and the other locating surface being provided on the main bodypart, at least the external surface of the nut part between the twolocating surfaces being provided with cooling fins, said nut part alsohaving an annular portion projecting from the locating surface thereontowards the tip of the nozzle element, which annular portion closelysurrounds the tip of the nozzle element and tapers in radial thicknessin a direction from the locating surface towards the tip and terminatesadjacent the tip in a sharp edge, said engine having also spaced wallswhich afford surfaces co-operating with said peripheral locatingsurfaces to locate the injector, and having means causing a flow ofcooling air between said walls, whereby cooling air flows over thecooling fins of the injector, and the one of said walls adjacent theengine combustion space which co-operates with the locating surface onthe not part, having a hole therein through which the nozzle elementprojects, the hole tapering to receive the annular projecting portion ofthe nut part with a small clearance.

References Cited in the file of this patent FOREIGN PATENTS 168,235Switzerland .e June 1, 1934

